A complete blood count (CBC) is a test that measures the levels of red blood cells (RBC), white blood cells (WBC) and platelets in a person’s blood. The CBC remains one of the most common blood tests performed today. It can provide important information about the types of blood cells present, their condition, number and percentage in relation to other cells.

The CBC test takes only a few minutes, and is performed by taking a blood sample from a patient. During this simple procedure, blood is withdrawn from the patient’s arm through a needle inserted into the vein. The blood sample is sent to a laboratory and analyzed.

The results of a CBC can help diagnose many conditions and diseases, including those related to the skin. For instance, high WBC levels may indicate tissue damage, such as that suffered after a burn. CBC testing can also help reveal the presence of conditions that may cause skin rashes, such as systemic lupus erythematosus or allergies.

In some cases, general itching (pruritus) is the result of a disease that can be detected with a CBC. Such conditions include hives, scleroderma and shingles.

There is generally no special preparation necessary for the CBC test. However, some medications may interfere with a CBC. Patients are urged to follow their physician’s orders carefully about how to take their medications before the test in order to ensure its accuracy.